On the shortening of Indian summer monsoon season in a warming scenario

C. T. Sabeerali, R. S. Ajayamohan

Research output: Contribution to journalArticle

Abstract

Assessing the future projections of the length of rainy season (LRS) has paramount societal impact considering its potential to alter the seasonal mean rainfall over the Indian subcontinent. Here, we explored the projections of LRS using both historical and Representative Concentration Pathways 8.5 (RCP8.5) simulations of the Coupled Model Intercomparison Project Phase5 (CMIP5). RCP8.5 simulations project shortening of the LRS of Indian summer monsoon by altering the timing of onset and withdrawal dates. Most CMIP5 RCP8.5 model simulations indicate a faster warming rate over the western tropical Indian Ocean compared to other regions of the Indian Ocean. It is found that the pronounced western Indian Ocean warming and associated increase in convection results in warmer upper troposphere over the Indian Ocean compared to the Indian subcontinent, reducing the meridional gradient in upper tropospheric temperature (UTT) over the Asian summer monsoon (ASM) domain. The weakening of the meridional gradient in UTT induces weakening of easterly vertical wind shear over the ASM domain during first and last phase of monsoon, facilitate delayed (advanced) monsoon onset (withdrawal) dates, ensues the shortening of LRS of the Indian summer monsoon in a warming scenario.

Original languageEnglish (US)
Pages (from-to)1609-1624
Number of pages16
JournalClimate Dynamics
Volume50
Issue number5-6
DOIs
StatePublished - Mar 1 2018

Keywords

  • CMIP5
  • Global warming
  • Indian summer monsoon
  • Length of rainy season
  • Onset and withdrawal dates
  • RCP8.5

ASJC Scopus subject areas

  • Atmospheric Science

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